1. Field of the Invention
The present invention relates to an optical switch, and particularly to an optical switch having an improved sealing structure.
2. Description of Related Art
An optical switch is a passive optical component for switching optical signals between input fibers and output fibers, and is widely used in optical transmission systems and in optical networks. To assure good performance of the optical switch, the influence of the environment on the switch has to be reduced. Hence, a good sealing structure to protect the optical elements in the switch is increasingly important.
A sealing structure for an optical component must provide good stability and isolation, so must exclude dust and vapor from an inside of the optical component. Present sealing structures for optical components mainly use epoxy resin to mount fibers into two housings, with the two housings being engaged together by screws. Such sealing structures provide a low level of isolation, which fails to exclude vapor and dust from an interior of the optical component. Optical efficiency of the optical component is, therefore, at risk.
Other sealing structures use a rubber-ring situated at entrances and in junctures between housing halves to achieve a seal. Such rubber-rings are designed to conform to a shape of the entrances and junctures and commonly define circular openings for receiving fiber clamps holding the fibers. However, pressure exerted on the rubber-rings by the fiber clamps is asymmetrical because, although the circular groove of the fiber clamp initially exerts a symmetrical pressure against the circular opening of the rubber-ring, the additional pressure acting against the rubber-ring exerted by the two housing halves when the two housing halves are bound together results in an asymmetric stress in the rubber-ring at the openings. The added stress will result in accelerated aging of the rubber-ring, leading to breakdown and a loss of sealing characteristics over time. This will allow vapor and dust to enter into the optical component, degrading optical efficiency.
For the above reasons, an improved sealing structure for optical components is desired which provides dependable isolation.
An object of the present invention is to provide an optical switch having an improved sealing structure.
Another object of the present invention is to provide a sealing structure for optical components having good stability and high isolation from the environment.
An optical switch having a sealing structure and connecting to input fibers and output fibers comprises a switching device, a top housing, a bottom housing, a gasket, and a plurality of fiber clamps.
The top housing and the bottom housing are similar in shape and when fit together have substantially a bottle shape. The top housing and the bottom housing each define a channel for receiving the gasket. The gasket defines at least one elliptic opening for receiving a fiber clamp holding a fiber. The gasket is received in the channels of the top and bottom housings, and fills the channels when pressure is applied by screws combining the top and bottom housings together. Good isolation is achieved in a space defined between the top and bottom housings.
A similar sealing structure can be used to protect other optical components, such as optical couplers, optical connectors and optical attenuators.
Other objects, advantages and novel features of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.